<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <form action="/register" method="post">
        <p>
            用户名：<input type="text" name="username" />
        </p>
        <p>
            <button>提交</button>
        </p>
    </form>
</body>
</html>